Crash sensor. An important part of the airbag system, its function is to detect and judge the impact signal after the car collides, so as to decide whether to deploy the buffer airbag. There are mainly three types of mechanical sensors for collision sensors, which are used more in early airbags. The principle of inertia is mainly used, and the inertial force of the components in the sensor is used to overcome the spring force to trigger the gas generator. The mechanical type ensures that the airbag will not be activated when the acceleration is low, and the reliability is high; but it can only be sensed at a single point, which requires extremely high quality, precision and wear resistance of the mechanical parts.